Which of the following is a sign of wound infection?

Redness is a common sign of wound infection because it indicates inflammation in response to an invader, such as bacteria. When a wound becomes infected, the body's immune response kicks in, causing increased blood flow to the area. This results in the characteristic redness as well as warmth, swelling, and pain. In addition to redness, other signs may include pus formation, increased drainage, and the presence of fever, which further point to an infection.

Other options, while they may occur in various contexts, do not specifically point to infection. Dryness could indicate healing or a lack of moisture but not an infection. Increased fatigue can be a vague symptom related to a variety of conditions and is not specific to wound infections. Coolness at the site might suggest poor circulation or a lack of blood flow rather than an infection. Therefore, redness stands out as a clear indicator of a wound infection.